Enabling screen sharing on iPad Air
Unable to access screen sharing on IPAD AIR when on the iPad with apple support
[Re-Titled by Moderator]
iPad Air, 18
Having myself had a remote support session with Apple Support some time ago, from recollection, the session with support team merely required that I click a "consent" that appeared on the screen of my iPad. I don't recall screen sharing using any of the commercial Apps.
As such, I can only conclude that the screen-share was something specific to Apple Support. With available information, I can only conclude that your local network connection may have been dropping network traffic (by IP Address or Port) for a reason that we'll not be able to remotely diagnose.
As for your issue with Messages, I presume that you refer to the native Messages App - and message forwarding...
An iPad, whether a Cellular model or not, is not capable of directly accessing Cellular Voice or SMS/MMS Messaging features. An iPad with either WiFi or Cellular connectivity alone can only access IP-data services. However, when paired with an iPhone, the capabilities of iPad broaden to include access to Cellular Voice and Messaging services of the associated iPhone - relayed to the iPad over WiFi using Apple’s continuity features.
More information about Continuity and the relevant Cellular services can be found here:
Continuity
Use Continuity to connect your Mac, iPhone, iPad, iPod touch and Apple Watch – Apple Support
SMS/MMS Messaging
If you have an iPhone - and both iPad and iPhone are signed-in to iCloud with the same AppleID - to send or receive SMS/MMS messages (green bubbles) using your iPad you must explicitly enable Text Message Forwarding for your iPad on your iPhone...
On your iPhone:
Settings > Messages > Text Message Forwarding - set to ON - and explicitly enable your iPad from the list of devices.
Also ensure that Messages in iCloud is enabled on both your iPhone and iPad:
Settings > [Your Name / AppleID] > Messages - set to ON
